The present invention relates to a rotary magnetic sensor for magnetically detecting rotation of a rotary member such as a rotary shaft and for generating electrical signals, particularly electrical pulse signals, corresponding to the rotation of said rotary member.
Heretofore, rotary sensors of this kind have been roughly classified into brush systems and optical systems. The rotary sensor of the brush system is simple in construction but it is inferior in resolution and response characteristics and tends to degrade reliability due to mechanical wear since a sensor of this type relies upon the electrical contact of the sensor with a rotary member. The rotary sensor of the optical system is superior in resolution due to the application of optical techniques now widely used in the art. However, the rotary sensor of this type is adversely affected by mechanical shock, vibration, dusty environment and contamination by oil or the like, and the range of temperature where the sensor of this type can be employed is substantially limited.
In order to avoid the defects in the rotary sensors of the brush type and the optical type, a rotary magnetic sensor has been proposed. The rotary magnetic sensor heretofore proposed employs a disk made of magnetic material having slits cut around the periphery thereof or a disk made of non-magnetic material having one or more magnets or iron pieces embedded in the periphery thereof and a magnetic sensitive element combined with said disk to generate electrical signals in accordance with the rotation of the disk. The rotary magnetic sensor of the prior art has a simple construction and attains its purpose, but it is impossible in such conventional construction to provide a plurality of electrical signals, such as pulses, per one revolution of the disk.